Telephone-exchange system



` Hume 19,1924o A. RAYNSFORD TELEPHONE EXCHANGE SYSTEM Filed May 4c` 1921 v Vl mf VIT @il MYEH u LLv-III LIP //7 Ver? for Aff/7W Hay/75 fo rd,

VSE 1w ITI Patented June 1G, 1924.

Mieli? if* l STAT i iastate ARTHUR RAYNSFORD, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COIM- PANY, NCORPOR-ATED, OF NEW YORK, N, Y., A CORPORATION OFl NEWT TELEPHONE-EXCHANGE svsrnivr.

Application filed May 4, 17921. Serial 466,827.

T 0 all whom it may cm1-cern.'

Be itknown that I, ARTHUR RAYNsroRD, a citizen of the United States, residing at New York, in the county oiz Bronx, State of New York, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a -full, clear, concise, and exact description.

This invention relates to a telephone exchange system wherein automatic and manual oliices are interconnected by trunks which may be selected by subscribers of the automatic oiiice `from certain levels of the selectors whena connection is desired with a subscriber in a manual oiiice. The trunks terminate at the manual oiiice before operators who complete the connections.

l The object of the invention is to provide a circuit arrangement which will take'care otk all the necessary operations in calls ort this character with interotiice trunks having only two conductors.

Referring to the drawing, which shows only so much of a telephone exchange system as is necessary tor a comprehension ot the invention, the invention will more readily be understood from a detailed description of the operation.

Uponthe 4removal ot the receiver by thev calling party at substation A associated with the automatic oiiicevhis line is automatically extended in the well-known manner by line iinder 1 to a first selector 2. The subscriber now operates his dial 3 to set the first selector opposite a group of trunks terminating in the desired manual oiiice whereupon the selector automaticallyT seizes one of these trunks. The relay 4 now opcrates over the calling line circuit and operates aslow relay 5 which in attracting its outer left armature applies tone from source 6 to the calling line to notify the calling subscriber that his line has been extended to a trunk leading to the manual oiiice. Relay 5 at its middle lett armature applies ground potential to the test multiple 7 of the seized trunk which ground potential will be maintained after the calling subscriber restores his receiver and releases selector 2 as will be explained in detail and will be removed only when the operator at the manual office disconnects from the other end of the trunk, thus, insuring that this trunk will not ibe selected unless it is idle. The apparatus to the left ot the dotted line is located in the automatic office and the apparatus tothe right is located atthe manual oiiice. The attraction ot the right armature of relay '4 closes a loop including the trunk conductors in series to operate a relay 10 at themanual otiice tor lighting a calling lamp 16 thereby indicating the arrival of the call at the operators position. This circuit is as follows:

Free pole of battery, normal contact of relay 8, resistance 9, relay 10, lower normal contact ot' relay 29, lower trunk conductor, conductor 11, right contact of relay 4, relay 12, right winding of polarized relay 13, resistance 14, upper trunk-conductor, upper normal contact'of relay 29,* and marginal relay 15 to ground. Relays 12 and 15 are marginal and do not operate in this circuit,.but relay 10 operates and lights the calling lamp 16. y,The operator in response to the lighting ot this lampinserts vtheanswering plug into the answering jack which operates relay 17 over an obvious circuit. Answering supervisory lamp 24 also lights. Relay 17 operates relay 18. Relay 18 in attracting its right armature extinguishesthe calling lamp 16 and in attracting its inner leftarmature short-circuits the resistance 9, which reduces the resistance .of the above traced circuit and results in the operation ot' the marginal relays 12 and 15. Relay 12, operates slow releasing relay 19 which in attracting its outer lett armature disconnects the tone source from the calling line and in attracting its inner lett armature closes a' circuit for relay 5 to hold the same energized independently of the condition of relay 4. Relay 15, at the manual oiiice, in operating closes a bridge, including a retardation coil 20, across the trunk beyond the condensers 21 and 22 thereby completing a circuit for and operating the answering supervisory relay 2,3 to extinguish the answering lamp 24v by means of a shunt circuit. The operator now presses her listening key 25, ascertains the desired number and completes the connection inthe wellknown manner. Upon the response of the subscriber at substation B in the `manual oiiice, relay 26 operatesand extinguishes the calling supervisory lamp. 27 in the usual manner. V

The subscribers may now converse, talking battery being supplied to the substation B from the cord circuit in the manual office 13 operates and in attracting its armature operates relay 30 to reverse the direction of current ilew in the calling line to operate the message register or coin collector (not shown).

'Upon the replacement of the receiver by Athe party at substation A, relay et releases.

In retracting its right armature, this relay removes the short circuit from the high resistance relay 31, which is now included in theloop circuit, releasing marginal relay 15 at fthe manual otlice, which in retracting its armature opens the bridge across the trunk including the retardation coil 20. The answering supervisory' relay 23 releases causing the lighting of lamp 2%-v to notily the operator that the subscriber at substation A has replaced his receiver. The replacement of the receiver by the party at substation A releases the finder 1 and selector 2 in the well-known manner, but since relay 31 is operated, relay 19 is held operated which in turn holds relay 5 operated. Relay 5 at its middle le'ft armature holds ground on the test multiple 7 to prevent it from being seized before the' operator has removed the plug. When the plug is removedy from the trunk jack relay 31 releases, releasing relay 19 which in turn releases relay 5 to remove the busy condition from multiple 7. The removal of the plug also deenergizes relay 13 which in releasing releases relay 30 to restore the normal connections of the battery to the trunk. The removal of the plug also releases relay 17 which in turn releases relay 18. Relay 18 in retracting its right armature unlocks relay 29, which restores the normal connections oi the battery to the trunk" at the manual otiice. Relay 18 in releasing its outer left armature releases relay 8 which restores the normal connection ot resistance 9 to the battery and in retracting` its inner left armature removes the shunt from around said resistance. The function of the slow releasing relay 8 is to prevent the accidental locking or" relays 10, 31, 12, 13 and 15 in the loop circuit when the operator withdraws the plug. Due to relay 8 being slow' to release it maintains battery disconnected from relay 10 until after relay 31 has released long enough to deenergize relay 19 which in retracting its right armature opens the loop.

Inasmuch as relay 5 is locked under con` trol of relay 19 which is in turn controlled by the operator, the calling party can flash the lamp 24 while the plug isin the trunk jack without releasing the connection, and thus secure the attention of the operator it he should so desire.

What is claimed is:

1. In a telephone system, the combination with automatic and manual ollices, oi' telephone lines terminating therein, trunks each consisting of two conductors only for interconnecting said ollices, automatic switches controlled by the calling subscriber tor selecting one ot said trunks, means for' automatically connecting a tone source at the automatic office to the calling line upon the selection ot said trunk, a lamp at the manual otlice, means tor lighting saidlamp upon the selection of said trunk and means actuated. by the operator in response to the call for disconnecting tinguish'ing said lamp.

2. ln a telephone system, the combination with automatic and manual offices, of tele phone lines terminating therein, trunks each consisting o't two conductors only for interconnecting said olces, automatic switches controlled by the calling subscriber for selecting one ot' said trunks, a lamp associated with said trunk at the manual olice lighted by the selection ot said trunk, a link circuit adapted tokbe connected to said trunk by the operator and having a supervisory relay therein, a bridge across said trunk, a trunk relay operated by the connection of said link circuit to said trunk, a circuit including said bridge closed by said trunk relay for operating said supervisory relay, a lamp in said link circuit extinguished by the operation of said supervisory relay, and means controlled by the calling subscriber in replacing his receiver for releasing said trunk relay to deenergize said supervisory relay to light said lamp. Y

3, 1n a telephone system, the combination with automatic and manual offices otitele` phone lines terminating therein, a trunk consisting of two conductors only for interconnecting the same, a loop circuit including said trunk conductors in series, a relay in said circuit at the manual otlice, a pair of i condensers in said trunk at the manual oliice, a bridge across the trunk beyond said condensers, a link circuit having a supervisory relay adapted to be connected to the trunk by the operator in responding to the call, means actuated by the connection of said llinkV circuit to said trunk for reducing the resistance of said loop to operate said marginalrelay to close said bridge to operate said supervisory relay, and a relay at the automatic oflice in circuit with the calling line for controlling said loop circuit.

4. In a telephone system, the combination with automatic and manual offices, of telephone lines terminating therein, trunks each consisting of two conductors only for interconnecting said ollices, automatic switches said source and exllf) controlled by the callin subscriber forselecting one of said trun s, means orautomatically connecting a tone source at the automatic olice to the calling line upon -the selection oi' said trunk, a lamp at the man-- ual otiice lighted upon the selection of said trunk, a maii'ginal relay at the automatic o'liice, and an energizing circuitthereior includingpsaid trunk conductors in series` closed by the operator in responding to the call for disconnecting said tone source.

5. In a telephone system, in combination with automatic and manual oiices, telephone lines terminating therein, trunks each consisting of two conductors only for interconnecting said offices, automatic switches controlled by the calling subscriber for selecting one of said trunks, means for applying a tone at the automatic oiice to the calling line upon the selection of the trunk, a loop circuit including said trunk conductors, a marginal relay at the automatic oiiice and a marginal relay at the manual oliice, a bridge across the trunk at the manual oiiice controlled by said latter relay, a supervisory relay, a lamp controlled thereby, a circuit for said relay including said bridge, and means actuated by the operator in responding to the call for reducing the resistance of said loop circuit to o erate said marginal relays to disconnect sait tone source and extinguish said lamp.

6. In a telephone exchange system, the combination with automatic and manual o'liices, of telephone lines terminating therein, trunks each consisting of two conductors only interconnecting said oiiices, automatic switches controlled by the subscribers at the automatic oitice for selecting one of said trunks, a loop circuit including said trunk conductors in series, two relays including said loop circuit in the manual office, one of which is marginal and the other non-marginal said non-marginal relay being operated upon the seizure of the trunk, a calling lamp lighted thereby, a pair of condensers in said trunk beyond said marginal relay, a bridge across the trunk beyond said condensers, a link circuit adapted to be connected to the trunk by the operator in responding to the call, means actuated thereby for reducing the resistance of said loop circuit to operate said marginal relay to close said bridge, a supervisory relay in said link circuit controlled by said bridge, and a relay at the automatic oiiice in series with the calling line for controlling said loop circuit.

7. In a telephone system, the combination with automatic and manual offices, of telephone lines terminating therein, trunks each consisting of two conductors only interconnecting said ofiices, automatic switches controlled by the calling subscriber for selecting one or" said trunks, means for automatically connecting a tone source at the automatic oiiice to the calling line upon the se'-- lection of said trunk, a loop circuit including said trunk conductors, a marginal relay at the automatic otiice controlling said tone source, and a marginal relay at the manual otiice, means Vfor closing said circuit upon the seizure of said trunk, a link circuit adapted to be connected to said trunk and having a supervisory relay therein, means for controlling said supervisory relay by said last named marginal relay, means actuated by the connection of said link circuit to said trunk for reducing the resistance of said loop to operate said marginal relay, and a relay at the automatic oiiice in series With the calling line Jfor controlling said loop circuit.

8. In a telephone system, in combination With automatic and manual ofiices, telephone lines terminating therein, trunks each consisting of two conductors only for interconnecting said oliices, automatic switches controlled by the calling subscriber forselecting one of said trunks, a relay in said trunk operated upon the seizure thereof for placing a busy condition on the seized trunk, a loop circuit including the trunk conductors in series, and a relay therein at the automatic oiice for independently holding said busy relay operated, the continuity of said loop circuit being controlled solely from the manual ofiice. t

9. In a telephone system, a pair of oiices, a telephone line, a circuit for connection therewith, a trunk having two conductors only interconnecting said'ofiices, a relay operated upon the extension of said line to said trunk at the originating oiiice for connecting said circuit to said'line, a link circuit adapted to be connected to the trunk at the distant office, a circuit including said link, a marginal relay controlling the same, a marginal relay in said trunk at the distant office, a loopl circuit including said trunk and marginal relays for energizing the same closed upon the connection of said link circuit to said trunk, means actuated by one of said marginal relays for disconnecting said first mentioned circuit from said line and means actuated by the other for closing the circuit including said link, a supervisory relay in said link circuit and means for operating the same upon the closure of said circuit.V

10. In a telephone system, a pair of ofiices, a telephone line, a circuit for connection therewith, a trunk having two conductors only interconnecting said oliices, a relay operated upon the extension of said line to one end of said trunk for connecting said circuit to said line, a link circuit adapted to be connected to the trunk at the other end, a circuit including said link, a marginal relay controlling the same, ,a marginal relay at the other end of said trunk, a loop circuit including said trunk and marginal relays for energizing the Same closedrupon the connection of said link clrcuit to said trunk, one of said marginal relays disconnecting said first' mentioned circuit from said line and the other closingl the circuit including` said link, a supervisory relay in said link circuit operated by the closure of said circuit, a line relay in said telephone line controlling said loop circuit, a high resistance relay, and a short circuit about the saine closed by said line relay and opened h3." the releaee thereof to include said high resistance relay in said loop circuit to release said marginal relay at the other end of said trunk to open the circuit including saidlink to release Said supervisory rela-y.

ln Witness whereof, I hereunto subscribe my naine this 2nd day of May, A, D. 1921.

ARTHUR RAYNSFORD 

